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2.Numericalproblemanalysis
sourcefunctionµshouldaimatzero.Basedonequation(2.54)andtheabovecon-
siderationsitmaybeconcludedthatthedistributionoftheadjointvariablepinthe
studiedobjectreflectstheinfluenceofthefiniteelementpositiononthesensitivity
ofthedecisionvariablesintheseelements.Thenecessaryconditionfortheobjec-
tivefunctionFj=Fj(uj)tohaveatleastalocalminimumatthepointγ*istozeroat
thispointofitsgradient.Intheadjointequationtothestateequation,theright-hand
vectoriszeroedifthepotentialsinthegridnodestowhichthevoltageelectrodes
adhereareequaltothecalculationwhichhasbeencalculatedfortheprocess.Such
astatewilltakeplacewhentheelectricalconductivitydistributiondeterminedin
agiveniterativestepintheobjectcoincideswiththeactualdistributionofelectrical
conductivity.ForthezerovectoroftherightsidesintheconjugateequationandDi-
richlet’suniformboundaryconditionsforthisequation,theelementsoftheadjoint
vectorpjareequaltozero.Thenalloftheelementsofthegradientvector
willbe
zero.Duetothefactthatthesameobjectisexaminedatdifferentprojectionangles,
zerogradientvectors
willappearsimultaneouslyforallprojectionangles.This
fulfilsthenecessaryconditionfortheminimumoftheobjectivefunction(localmin-
imum).Individualvaluesofcorrectionsdeterminedforallprojectionanglesgive
totalcorrectionsofelectricalconductivityforthemeshnodesofthetestedobject.
